Polyethylene glycol (PEG)-induced drought causes stress responses in growth and photosynthesis of common beans ( <i>Phaseolus vulgaris</i> L.)

Summary The aim of the study is to evaluate the effects of polyethylene glycol (PEG)-induced drought stress on the morphological and photosynthetic traits of common bean ( Phaseolus vulgaris L.). This study systematically investigated the morpho-physiologic and biochemical responses of five common bean genotypes under controlled PEG-induced drought conditions (10% and 15% PEG). Mild drought stress (10% PEG) elicited significant adaptive responses, including enhanced root elongation, shoot growth, and biomass accumulation in select genotypes, notably G4 and G5, which also sustained higher chlorophyll content and protein accumulation. Conversely, severe drought (15% PEG) markedly impaired growth parameters and photosynthetic efficiency, reflecting stomatal and non-stomatal limitations. Correlative analyses demonstrated strong interrelationships among photosynthetic pigments, biomass traits, and gas exchange parameters, while principal component analysis elucidated distinct trait clusters underlying drought tolerance mechanisms. Elevated water use efficiency under moderate stress further underscores genotype-specific drought adaptation strategies. These findings highlight the complex interplay between morphological and physiologic traits in conferring drought resilience, offering critical insights for breeding programs aimed at enhancing common bean performance in water-limited environments.